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(cont.)
An analysis of amphibians in China by Xie et al. (2007)
showed that 100 species are extinct or threatened and 23
species are projected to have deteriorated in their Red List
category since 1980,6 i.e. they have declined rapidly. The
South China (i.e. Guangdong, Guangxi, Hainan and Hong
Kong SAR) amphibian fauna has a threatened percentage
(25%) similar to the national total (27.3%) and there are
one Critically Endangered, eight Endangered and 16
Vulnerable species (see Table 1). The vast majority of the
threatened South China amphibians are associated with
forests and/or streams, making them especially susceptible
to habitat loss and degradation caused mainly by
deforestation in the past. The construction of hydro-dams
poses a more recent and additional threat to the stream
species. Chinese Giant Salamander Andrias davidianus and
the spiny frogs belonging to the genus Paa are collected
for the commercial food trade, making over-exploitation
their main threat. These commercially valuable amphibians
are the only South China species identified by Xie et al. to
have declined rapidly since 1980.6
Table 1: The number of Chinese amphibian species in the IUCN Red List Categories
| Red List Category |
China* |
South China |
| Extinct |
1 |
- |
| Critically Endangered |
8 |
1 |
| Endangered |
39 |
8 |
| Vulnerable |
52 |
16 |
| Near Threatened |
35 |
9 |
| Least Concern |
166 |
61 |
| Data Deficient |
65 |
5 |
| Total |
366 |
100 |
| % threatened or extinct |
27.3% |
25% |
Xie et al., 20076*
Although much has been learnt about the amphibians
from the Red List Assessment and the RLI analysis,
there are still some obvious gaps. Amphibians have been
completely assessed only once, in 2004, and the RLI
analysis is only preliminary as the 1980 Red List categories
had to be retrospectively assigned by considering the 2004
criteria and information on the threats. In order to gain a more accurate picture of the change in their status, and
thus determine progress with respect to the 2010 Target
of significantly reducing the rate of biodiversity loss, the
amphibians need to be re-assessed and this is now being
carried out by the IUCN SSC Amphibian Specialist
Group. The accuracy of this new assessment depends on
the availability of up-to-date distribution, population,
trends and threats information. It is probably too ambitious
to launch a nation- or region-wide survey to gather data
for all the species but in fact a lot of information has been
gathered by researchers, teachers, students and naturalists
since the last assessment. These data should be published
so that they will become available and can be used in
the assessment process. In particular, information for the
Data Deficient species are needed so they can be properly
assessed.
Attention should also be paid to 'unexplained' declines
or disappearances of amphibian populations. The
phenomenon of amphibians that have 'suddenly'
disappeared from places where the habitats remain intact
has occurred particularly in South and Central Americas
and Australia, but is not reported in Asia. It took scientists
more than ten years to figure out that a lot of these
declines are linked to chytridiomycosis, a disease caused by
the chytrid fungus. Some amphibians have become extinct
because of this disease while others are merely carriers and
are apparently not affected by the fungus. Up until recently,
the very few, small-scale studies in Asia (e.g. Rowley et al.,
20077) did not find this fungus. However, during the Joint
Meeting of the 3rd Meeting of Asian Society of Veterinary
Pathology & the Association of Asian Veterinary Schools
in August 2007, Dr Y. Une reported finding the chytrid
fungus in wild amphibians in Japan. So it seems Asia is
not immune to this pathogen and its impact on native
amphibians is yet to be seen. If readers of Living Forests
have observed 'unexplained' declines of amphibians or
found large numbers of dead amphibians in the field, they
are requested to kindly contact the author.
Small hydro-dams constitute
new threats to stream-dwelling amphibians |
Another global phenomenon that is likely to have
increasing impact on the amphibians and other biota is
climate change. The generally agreed prediction for South
China is that the temperature will increase in both summer
and winter and there will be more extreme weather events.
The implications for the regional amphibians are not clear
but it is expected that the high-altitude species will be
more at risk as their preferred micro-climate and habitat
will recede up the mountains as it gets hotter. In Europe
climate change has also been found to tip key habitats into
optimal temperature conditions for chytrids, precipitating
frog and salamander population collapses.8 Changes in
the distribution and communities of amphibians in high
altitude areas are something worth looking into.
For amphibians, as for other groups, the effectiveness of
the Red List Index in indicating biodiversity trends will
depend on the quality of information from the field -
there is a place for reserve staff, academics and naturalists in
understanding distribution, ecology, trends and threats. The
prospects for steering species from extinction depend on
understanding and countering these threats.
References
- Butchart SHM, Stattersfield AJ, Bennun LA, Shutes SM, Akcakaya
HR, Baillie JEM, Stuart SN, Hilton-Taylor C and Mace GM, 2004.
Measuring global trends in the status of biodiversity: Red List Indices
for birds. PLoS Biology 2: e383.
- Butchart SHM, Akcakaya HR, Chanson J, Baillie JEM, Collen B,
Quader S, Turner WR, Amin R, Stuart SN and Hilton-Taylor C,
2007. Improvements to the Red List Index. PLoS ONE 2(1): e140.
- Butchart SHM, Stattersfield AJ, Baillie JEM, Bennun LA, Shutes
SM, Stuart SN, Akcakaya HR, Hilton-Taylor C and Mace GM, 2005.
Using Red List Indices to measure progress towards the 2010 target
and beyond. Philosophical Transactions of the Royal Society B 360:
255-268.
- IUCN, Conservation International Center for Applied Biodiversity
Science and NatureServe, 2004. IUCN Global Amphibian Assessment. http://www.globalamphibians.org
- Stuart SN, Chanson JS, Cox NA, Young BE, Rodrigues ASL,
Fischman DL and Waller RW, 2004. Status and trends of amphibian
declines and extinctions worldwide. Science 306: 1783-1786.
- Xie F, Lau MWN, Stuart SN, Chanson JS, Cox NA and Fischman
DL, 2007. Conservation needs of amphibians in China: a review.
Science in China Series C: Life Sciences 50: 265-276.
- Rowley JJL, Chan SKF, Tang WS, Speare R, Skerratt LF, Alford RA,
Cheung KS, Ho CY and Campbell R, 2007. Survey for amphibian
chytrid Batrachochytrium dendrobatidis in Hong Kong in native
amphibians and in the international amphibians trade. Diseases of
Aquatic Organisms 78: 87-95.
- Bosch J, LM Carrascal, L Durhn, S Walker and MC Fisher, 2007.
Climate change and outbreaks of amphibian chytridiomycosis in
a montane area of Central Spain: is there a link? Proceedings of
the Royal Society B 274: 253-260. www.jcu.edu.au/school/phtm/PHTM/frogs/papers/bosch-2007.pdf
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